The control of the content is important in order to protect the programming from, for example, nonpaying customers. A conventional communications system, such as a cable television system, therefore, typically applies an encryption scheme to television content in order to prevent unrestricted access. Once a system operator chooses an encryption scheme, the operator installs all of the necessary headend equipment (e.g., Scientific-Atlanta's conditional access software and associated equipment). The receiving devices (e.g., set-tops) located at the subscriber's premises must be compatible with the encryption scheme in order to decrypt the content for viewing. Due to the proprietary encryption systems, however, an operator is prevented from installing different set-tops that do not have the proper decryption keys. If the operator wishes to install different set-tops that decrypt a different conditional access system, the operator would also have to install a second proprietary encryption system to overlay the incumbent encryption system in order to use both set-tops.
It would be to the operator's advantage to be able to select set-tops from any manufacturer and easily implement different encryption/decryption schemes in the system without duplicating the headend equipment and utilizing extra bandwidth. The present application is directed towards a conditional access system that enables different proprietary set-tops to decrypt content using different decryption keys.